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Welding joins two or more metal parts together with heat, pressure, or both to form a joint as the parts cool. MIG Welding units require a shielding gas to protect the melted wire used to form that joint from particles and contaminants in the air.
MIG (Metal Inert Gas) welding tanks have gauges that measure pressure and flow to determine the tank’s gas level. Once gauges reach a low level, the gas tanks need to be refilled or replaced to ensure the strength of future welds.
MIG welding is popular because it is a reliable, versatile, and relatively easy method to learn. Many people become proficient MIG welders quickly by following some simple advice. In this article, we will explore the MIG welding process, learn how to set the gas on a MIG Welder, and even look into welding without gas.
Signs Your MIG Welder Is Out Of Gas
Running out of gas during a project will cause a noticeable change in the consistency of the welding pool. This is because the gas protects the weld from environmental contaminants.
You will know you are out of gas when:
- Air bubbles form in the weld puddle
- Visible spatter in the joint
- Holes form in the weld
- Excess smoking or sparking occurs during the welding process
The consistency of the weld will change when there is no gas present because contaminants from the air create flaws in the joint.
How Do I Measure The Amount Of Gas In A MIG Welder?
There are a few simple ways to tell when it is time to replace a tank:
- Check gauges
- Weigh shield gas bottle
- Notes from last use
- The Hot water test
A MIG Welder uses regulators and a connected hose to joint the bottle of shielding gas to the unit. This gauge can be used to help you estimate the amount of gas remaining in the tank.
You can also check the weight of the tank. If you know the weight of the tank when it is full and empty, you can use its current weight to determine the amount of gas in the tank. Some experienced welders even claim they can do this simply by picking up the tank.
Keep track of the type of gas that you are using and the speed at which it travels on a chart or in a notebook to help determine when your gas level is low.
Finally, there is a quick and easy hot water test. Simply pour a container of hot water over the outside of the tank. You should be able to feel a change in temperature on the outside of the tank. The warm part of the exterior of the tank is the empty portion.
Choosing The Right Shielding Gas
Most MIG Welding projects lend themselves to a variety of shielding gas choices. You might need to consider your goals and materials to choose the correct one for your project. The following factors need to be considered when making your choice:
- The time needed to prepare and clean the surface area of weld properties
- The cost of shielding gasses and their purposes
- The properties of the base materials used for the project
- The purpose of the finished weld
The four most common MIG Welding gasses:
- Carbon Dioxide
Each gas has unique benefits and deficiencies depending on the project.
Carbon Dioxide (CO2) is the most common reactive gas and is often used in its pure form (some gasses require mixing with another gas). It is also the least expensive, making it a popular choice. Unmixed, CO2 has a very deep weld penetration for thick material. it can be less stable and may produce excess spatter when mixed with other gasses.
Oxygen is another reactive gas. It is often used when welding carbon, low alloy, and stainless steel. This requires a nine percent or less ratio mixed with another inert gas to improve the fluidity of the weld and its penetration. Oxidation can occur when welding certain metals. It is best to avoid aluminum, magnesium, copper, or other exotic metals.
When you need a clean weld, Argon is usually the top choice. Argon is most often mixed with CO2 in a 75 to 25 percent ratio. This creates a stable, controlled puddle with little spatter. This mixture’s clean look and a high rate of productivity create the narrowest penetration profile.
This makes it perfect for fillet and butt welds. Pure Argon is sometimes used in less rigid metals such as aluminum, magnesium, and titanium.
Helium, like Argon, is recommended for softer metals and stainless steel. Its wide, deep penetration profile is recommended for thick materials. Some projects require a mixture of Helium and Argon.
For stainless steel, a triad of shield gasses is required (Helium, Argon and CO2). Fast travel speeds and increased productivity are a result of Helium’s extremely hot arc. It is important to keep in mind that Helium is the most expensive gas and requires a very high flow rate.
Adjusting the profiles of any gas ratios will change the penetration, bead profile, and travel speed of the welding wire.
Changing the Gas Tank On A MIG Welder
It’s time to change the shielding gas tank on a MIG welding unit. This process requires some basic steps.
Use an adjustable crescent wrench to remove the regulator gauges and hose from the old tank. Immediately put a cylinder cap on the empty gas tank (they are pressurized and can cause accidents). Unclip the chain holding the tank to the welding unit and mark the tank as empty.
Now it is time to attach a new tank.
Make sure you chain the tank to the welding unit before removing the cap to avoid an accident. Next, open and close the valve cap quickly to clear the nozzle of any debris (you will hear a hissing sound). Using a crescent wrench, attach the regulator gauges and hose to the new tank.
Open the top valve and use the regulator gauges to check the gas pressure. Listen and use your hand to check for leaks before welding. After this step, you’ll want to turn on the welding unit and release the trigger gun. If the tank is attached correctly, you will feel air flowing out of the trigger gun.
Can You Use A MIG Welder Without Gas?
This question might seem a bit odd since a gas shield is needed to protect the weld puddle when using a MIG Welder.
But the answer is YES!
You can use a self-shielding MIG wire with a flux core. This special wire produces gas from burning flux as the wire melts. The heated flux in the wire produces a shielding gas that protects the weld.
This method is especially helpful in windy conditions where gas pressure would normally need to be increased. This can also allow for welding on dirty metals.
However, it is important to remember clean metals allow for a more visually appealing joint. You may also want to consider that gasless MIG Welding requires thicker wire so you may need a more powerful welding unit (usually 115-volt welder and above).
Most people choose MIG Welding units because they are easy to use and relatively quick to learn. Some hobbyists even compare them to using a glue gun. Overall, it is a low-cost and effective method of welding for those without extensive experience.